David Gilmour has performed "Comfortably Numb" at nearly every one of his solo concerts over the past three decades, and without Roger Waters onstage he's relied on everyone from Bob Geldof to Robert Wyatt to anonymous backup singers to handle the doctor's vocal parts. ("Just a little pinprick…") But when his On an Island tour came to London's Royal Albert Hall on May 29th, 2006 he brought out his greatest guest doctor to date: David Bowie.
It was two years after an onstage near-heart attack prematurely ended Bowie's Reality Tour and he'd kept a very low profile since then, popping up at an Arcade Fire gig and VH1's Fashion Rocks. Nobody even knew Bowie was in London, so the crowd was stunned when he came out near the end of Gilmour's set to sing the 1967 Pink Floyd classic "Arnold Layne." Bowie was a huge fan of Syd Barrett-era Floyd back when they were both part of the underground scene in mid-1960s London. He stuck around to join Gilmour on a spine-tingling rendition of "Comfortably Numb." It was the last time that Bowie ever performed in England. (In a strange coincidence, Barrett died a little over a month later.)
Pink Floyd keyboardist Richard Wright traditionally performed the Waters vocal part of "Comfortably Numb" during Gilmour solo concerts, but since he passed away in 2008 that duty has fallen on keyboardist Jon Carin. That musician is the Switzerland of the Pink Floyd universe in that he somehow manages to be in the solo bands for both Waters and Gilmour. That means he's played "Comfortably Numb" an absurd number of times, though on the Wall tour of 2010-2013, Waters himself obviously handled his own parts. Robbie Wyckoff was on hand to sing the Gilmour bits. All these complications could be easily solved if the surviving members of Pink Floyd simply toured together, though Waters and Gilmour have made it very, very clear that's never happening. For what it's worth, drummer Nick Mason is down.